Study on the Effect of an Intermittent Ventilation Strategy on Controlling Formaldehyde Concentrations in Office Rooms

Material emission and ventilation are two aspects influencing indoor air quality. In this study, a model predictive control (MPC) strategy is proposed for intermittent ventilation system in office buildings, to achieve a healthy indoor environment. The strategy is based on a dynamic model for predicting emissions of volatile organic compounds (VOCs) from materials. The key parameters of formaldehyde from panel furniture in the model are obtained by an improved C-history method and large-scale chamber experiments. The effectiveness of the determined key parameters is validated, which are then used to predict the formaldehyde concentration variation and the pre-ventilation time in a typical office room. In addition, the influence of some main factors (i.e., vacant time, loading ratio, air change rate) on the pre-ventilation time is analyzed. Results indicate that the pre-ventilation time of the intermittent ventilation system ranges from several minutes to several hours. The pre-ventilation time decreases exponentially with the increase in the vacant time, the air change rate, and with the decrease in the loading ratio. When the loading ratio of the furniture is 0.30 m2/m3 and the vacant time is 100 days, the required pre-ventilation time approaches zero. Results further reveal that an air change rate of 2 h−1 is the most effective means for rapid removal of indoor formaldehyde for the cases studied. The proposed strategy should be helpful for achieving effective indoor pollution control.

Analysis of air pollution in the City of Odesa using automated observation data

The work presents the analysis of air pollution in the City of Odesa using, among others, the data of automated observations. The air basin state was also evaluated using individual parameters of sustainable development. According to the official data of the recent years the City of Odesa belongs to the most polluted cities of Ukraine in terms of air pollution. Based on the ranking results it was established that the level of atmospheric pollution in the City of Odesa can be classified as high for the most of pollutants. It is classified as acceptable for some substances (sulfur dioxide and nitrogen oxide) and as extremely high for formaldehyde concentration. After comparing the observational data related to content of individual pollutants at the OSENU's observation point and the data of long-term observations in the city it was found that the content of nitrogen dioxide generally corresponds to the average long-term values. The observations conducted at the points of the city network indicated that the content of carbon monoxide is two orders of magnitude lower and the content of PM10 is one order of magnitude lower than dust concentrations. The increased content of certain pollutants in the air (nitrogen dioxide, carbon monoxide, etc.) is observed in the summer-autumn period and caused by the traffic intensification. The evaluation of the city's air basin state using individual parameters of the environmental measurement index showed that we observed better conditions in 2014 and 2016. The conditions for sustainable development are characterized by average indicators, however, towards worsening of the situation. The results obtained in this paper form a basis for extending the implementation of the Resolution of the Cabinet of Ministers of Ukraine on introducing a new procedure for state monitoring of the atmospheric air in Ukraine. The existing laboratory base of the observation points requires radical re-equipment. It is also necessary to conduct an air pollution survey for identification of high priority pollutants and, based thereon, development of monitoring programs with consideration of the necessity for keeping certain impurities under control.

An optimized ChIP-Seq framework for profiling of histone modifications in Chromochloris zofingiensis

The eukaryotic green alga Chromochloris zofingiensis is a reference organism for studying carbon partitioning and a promising candidate for the production of biofuel precursors. Recent transcriptome profiling transformed our understanding of its biology and generally algal biology, but epigenetic regulation remains understudied and represents a fundamental gap in our understanding of algal gene expression. Chromatin Immunoprecipitation followed by deep sequencing (ChIP-Seq) is a powerful tool for the discovery of such mechanisms, by identifying genome-wide histone modification patterns and transcription factor-binding sites alike. Here, we established a ChIP-Seq framework for Chr. zofingiensis yielding over 20 million high quality reads per sample. The most critical steps in a ChIP experiment were optimized, including DNA shearing to obtain an average DNA fragment size of 250 bp and assessment of the recommended formaldehyde concentration for optimal DNA-protein crosslinking. We used this ChIP-Seq framework to generate a genome-wide map of the H3K4me3 distribution pattern and to integrate these data with matching RNA-Seq data. In line with observations from other organisms, H3K4me3 marks predominantly transcription start sites of genes. Our H3K4me3 ChIP-Seq data will pave the way for improved genome structural annotation in the emerging reference alga Chr. zofingiensis.

Occupational Exposure to Formaldehyde and Cancer Risk Assessment in an Anatomy Laboratory

Dissecting a human cadaver is an irreplaceable practice in general training of medical students. Cadavers in anatomy laboratories are usually preserved in formalin, an embalming fluid whose basic component is formaldehyde (FA). The aim of this study is to assess the cancer risk of employees and students that are exposed to FA based on the results of three monitoring campaigns, as well as to suggest permanent solutions to the problem of FA exposure based on the results obtained. Three sampling campaigns of formaldehyde concentration in indoor environments were conducted at five different locations at the Anatomy Department of the Faculty of Medicine with the purpose of assessing permanent employees’ and medical faculty first year students’ exposure to FA. Indoor air was continuously sampled during 8 h of laboratory work and analyzed in accordance with the NIOSH Method 3500. Exceeding of the 8 h time-weighted average (8 h TWA) values recommended by Occupational Safety and Health Administration (OSHA) of 0.75 ppm was recorded in 37% of the samples during the three-month monitoring campaign. Cancer risk assessment levels for permanent employees were in the range from 6.43 × 10−3 to 8.77 × 10−4, while the cancer risk assessment levels for students ranged from 8.94 × 10−7 to 1.83 × 10−6. The results of the research show that cancer risk assessment for employees is several thousand times higher than the limit recommended by the EPA (10−6) and point to the importance of reducing exposure to formaldehyde through the reconstruction of the existing ventilation system, continual monitoring, the use of formaldehyde-free products, and plastination of anatomical specimens.

Simulation study on effects of purifier positions on formaldehyde removal under the condition of vehicle air supply

In order to further improve the interior air quality and comfort of the vehicle, CFD method is used to simulate the different airflow distribution caused by car-mounted air purifiers at different positions. Combined with the change of formaldehyde concentration field in car, the influence of car-mounted air purifiers on the formaldehyde dilution and removal under the condition of air conditioning air supply is analyzed. The simulation results are verified by actual measurement, and the trend of the simulation results is basically consistent with the measured results. When the car air purifier placed in the middle of the car roof, it can effectively dilute and purify the formaldehyde gas in the car, and reduce the concentration of formaldehyde in the breathing area of the driver and passengers. The adsorption and degradation of formaldehyde by the purifier, together with the dilution of formaldehyde by air supply, can improve the air quality in cars more effectively than using only one of the air purification methods.

Improving Formaldehyde Removal from Water and Wastewater by Fenton, Photo-Fenton and Ozonation/Fenton Processes through Optimization and Modeling

This study aimed to assess, optimize and model the efficiencies of Fenton, photo-Fenton and ozonation/Fenton processes in formaldehyde elimination from water and wastewater using the response surface methodology (RSM) and artificial neural network (ANN). A sensitivity analysis was used to determine the importance of the independent variables. The influences of different variables, including H2O2 concentration, initial formaldehyde concentration, Fe dosage, pH, contact time, UV and ozonation, on formaldehyde removal efficiency were studied. The optimized Fenton process demonstrated 75% formaldehyde removal from water. The best performance with 80% formaldehyde removal from wastewater was achieved using the combined ozonation/Fenton process. The developed ANN model demonstrated better adequacy and goodness of fit with a R2 of 0.9454 than the RSM model with a R2 of 0. 9186. The sensitivity analysis showed pH as the most important factor (31%) affecting the Fenton process, followed by the H2O2 concentration (23%), Fe dosage (21%), contact time (14%) and formaldehyde concentration (12%). The findings demonstrated that these treatment processes and models are important tools for formaldehyde elimination from wastewater.

Hygienic Assessment of Disposable Baby Diapers Made with Innovative Materials

Background: It is of current importance to develop an algorithm for assessing chemical and physical safety of products for children and adolescents made with such innovative materials as organic cotton, bamboo, fibers and threads containing silver ions used for children’s underwear, materials impregnated with marigold extract for insoles of children’s footwear, and diapers from plant raw materials. The institute conducts testing and scientific substantiation of children’s goods made using innovative technologies. Objective: To assess safety of diapers made with innovative materials (ECO-diapers). Materials and methods: We conducted physicochemical, toxicological and organoleptic testing of 200 samples of medium size disposable baby ECO-diapers made with innovative materials. Results: The results of chemical and toxicological tests of ECO-diapers in a model aqueous environment showed that the formaldehyde concentration in aqueous extracts of the diaper samples ranged from 0.08 ± 0.020 to 0.1 mg/dm3; toxicity index values – from 74.1 to 89.1 %; pH – from 0.35 to 0.5 units, and the total phenolic content – from < 0.005 to 0.024 ± 0.002 mg/dm3, thus being within permissible limits. Measured concentrations of acetaldehyde, acrylonitrile, acetone, benzene, hexane, methyl and propyl alcohols, toluene, ethyl acetate, lead, arsenic, zinc, chromium were also below threshold values. Chemical testing of the samples of baby diapers in a model air environment with exposure duration of 4, 12, and 24 hours detected migration of chemicals already after four hours of exposure, which did not change following 12 and 24 hours. The value of water absorption capacity, which is one of the main indicators of functional benefit of diapers, ranged from 307.6 ± 30.8 g to 355.5 ± 35.5 g and significantly exceeded the established standard (not less than 240.0 g for medium size diapers) owing to the use of innovative materials in the production of ECO-diapers. Conclusions: Our findings demonstrate the necessity to develop special methodological approaches to measuring breathability of ECO- and traditional diapers, to regulate smell by including this organoleptic quality criterion in the list of safety requirements, and to limit exposure duration in a model air environment to four hours.

Determination of Formaldehyde from Disposal of Formaldehyde Fixed Biological Specimen Buried in Soil

Biomedical waste specifically anatomical specimens and body parts will be incinerated by a local incineration facility. However, the incineration of formaldehyde fixed specimen from hospitals poses hazardous effect to human and environment due to an exposure of highly toxic gases such as dioxins and furans. In addition, this practise is considered as non-shariah compliance by Muslim community. Thus, a safer and shariah-compliance option to dispose anatomical specimens through deep burial has been introduced. The concern has been raised on the side effect of the formaldehyde treated specimen to the environment. Formaldehyde is used widely for preservation of surgical and anatomical specimens. The formaldehyde toxicity specifically on the soil, soil water, soil animals and plants should be considered after the burial of the anotamical specimens. Thus, the aim of this study was to investigate the side effect of formaldehyde on soil after the burial of formalin fixed specimen on the environment. In this study, the amount of soil elemental distribution and formaldehyde concentration of pre-burial and post-burial of biological specimen were evaluated by using Energy Dispersive X-Ray Fluorescence (EDXRF) and Ultraviolet-Visible Spectrophotometer instrument, respectively. For EDXRF analysis at Point C, soil elemental distribution after burial of dead biological specimens has higher concentration compared to before the burial. The concentration of formaldehyde at Point C was higher after the burial of dead biological specimen compared to before burial, which exceeds the tolerable concentration recommended by the World Health Organisation (WHO).

GENERATING A STREAM WITH A STABLE FORMALDEHYDE CONCENTRATION IN THE LABORATORY

A laboratory-scale bio-trickling filter (BTF) was initialized to evaluate the removal of formaldehyde biologically. However, generating formaldehyde gas in the lab is one of the grand challenges hindering research efforts. Formaldehyde was introduced into the gaseous phase by aerating the required air flowrate through a diluted formaldehyde solution mixed with methanol as a stabilizer by a bubbler. However, achieving stable gaseous influent concentrations of formaldehyde was challenging since it polymerizes while volatilizing. Resulting in paraformaldehyde. The resulting white powder clogged the pipes and generated uneven gaseous concentrations. To solve this problem, sodium hydroxide (NaOH) was added with a phosphate buffer to the aqueous formaldehyde solution to maintain the pH between 7.00-7.20. Additionally, the aqueous solution needed to be heated at 60℃ to eliminate the polymerization. The exhausted formaldehyde by volatilization was replaced by a continuous supply of aqueous diluted formaldehyde solution to keep the volume and mass of the aqueous solution and formaldehyde constant, respectively. Stable gaseous concentration was achieved for extended periods of time and verified by Fourier transform infrared (FTIR) spectroscopy.

Colorimetric pad for low-concentration formaldehyde monitoring in indoor air

PurposeThe purpose of this study was to develop an accurate, selective, low-cost and user-friendly colorimetric pad to detect formaldehyde at low concentration.Design/methodology/approach1-phenyl-1,3-butanedione, a reactive chemical, was selected to develop the colorimetric pad for indoor air formaldehyde measurement. Silica nanoparticle impregnated with the reactive chemical was coated on the cellulose filter surface to increase the reactive site. A certified formaldehyde permeation tube was used to generate six varied concentrations between 0.01 and 0.10 ppm in a test chamber. The color intensity on the pads was measured using an image processing program to produce a formaldehyde concentration reading chart. The colorimetric pad was tested for optimum reaction time, accuracy, precision, stability, selectivity and shelf life.FindingsThe color of the pads changed from white to yellow and the color intensity varied with the concentrations and appeared to be stable after exposure to formaldehyde for 8 hours. At room temperature, the stability of the pad was 7 days, and shelf life was 120 days. The accuracy, precision and bias of the pad were 12.38%, 0.032 and 6.0%, respectively. Carbonyl compounds, benzene and toluene did not interfere with the reading of this developed colorimetric pad.Originality/valueThe developed colorimetric pad meets NIOSH's criteria for an overall accuracy of ±25%, bias = 10%. They were accurate at low concentrations, user-friendly and had low cost compared to an electronic direct reading instrument (cost of chemicals and materials was 21.50 Bath or 0.69 USD per piece) so that favorable for the use of general people for health protection.